As shown in FIG. 1, the conventional keyswitch 10 of computer keyboards comprises a key top 11a, a rubber cone 12a, a first lever 13a, a second lever 14a, a base 16a, and a bottom board 22a. The first lever 13a and the second lever 14a are in scissors arrangement. Shafts 18a and 19a at the bottom ends of the first lever 13a and the second lever 14a are respectively pivotally arranged within pivotal grooves 20a and 21a installed at the top of the base 16a. The top ends of the first lever 13a and the second lever 14a are connected to the key top 11a. The first lever 13a and the second lever 14a form a jointly moving mechanism. The rubber cone 12a is disposed within the key pressing stroke of the key top 11a. When the key top 11a is guided to move upwards or downwards via the two levers 13a and 14a, the rubber cone 12a can press or leave a membrane circuit 15a to let a switch be on or off. However, the keyswitch 10a, the base 16a, the first lever 13a, and the second lever 14a all have a certain thickness such that the total height of the keyswitch 10a is increased. The compactness requirement of modern products can not be achieved.